The invention relates to the field of inkjet printing and, more specifically to an inkjet apparatus and a method for printing a plurality of pixels.
In the field of inkjet printing, for example in the field of large format printing of CAD plots or the like, when printing black lines only, the throughput for printing may be increased by using a dual pigmented black print head, also referred to as dual matte black print head or DK print head. In such a print head two separate reservoirs are provided and ink is supplied from these reservoirs to associated sets of inkjet nozzles by two trenches filled with matte black ink from the reservoir. The ink is fired from these trenches, more specifically from the respective sets of inkjet nozzles associated with the respective trench. This allows printing at the double carriage speed while maintaining firing frequencies for the print head which remain within acceptable ranges. This increases the throughput when printing for example line art only, like black line CAD plots as they are generated for example by architects.
One problem with pigmented inks used in thermally actuated print heads is that in case the print head has been idle for a specific time, for example for more than one second, ink drops with a correct volume and shape may only be obtained after having fired a few drops immediately before. Typically, three ink drops are enough to get a good drop volume and shape. The lack of appropriate volume or shape may result in a line roughness of a printed line that is clearly visible to the user in the printout or hard copy.